The present invention relates, in general, to a root canal plugging apparatus for dental work and, more particularly, to a complex root canal plugging apparatus consisting of a controller, a gun-type injection device, and a pen-type vertical spreader. The invention provides improvements in the pen-type vertical spreader and in the gun-type injection device.
Root canal plugging is the last procedure of treating and curing processes for the root canal, and one of the essential processes.
During a dental treatment for a decayed tooth in a dental clinic, a dentist appropriately removes decayed parts from the tooth using dental drills, reamers, files and burs, and performs a root canal plugging procedure for packing a root canal with a filler material, prior to covering the tooth packed with the filler material using a crown.
Typically, Gutta-Percha cones have been preferably used as such filler materials during the root canal plugging procedures. The Gutta-Percha is the milky juice of Malaysian trees of the sapodilla family, especially Palaguium or Payena trees, and has a semisolid phase at a normal temperature, but becomes a hard rubberlike gum when being compressed or heated. The Gutta-Percha in the form of such a hard rubberlike gum is so-called “white Gutta-Percha”. The dentally usable Gutta-Percha cones are produced by adding zinc oxide, barium sulfate, wax and pigment to the Gutta-Percha, and kneading them in a mixer prior to extruding the mixture in the form of a sheet using a roll. The sheet type extruded mixture is, thereafter, cut into pieces, and the pieces are shaped into cones to form desired Gutta-Percha cones having different sizes. The Gutta-Percha cones have been most widely used as the root canal filler materials since they are biologically compatible with living bodies and not harmful to the root apexes of human teeth.
A key point of the root canal plugging procedure is to plug the root canal tightly with Gutta-Percha cones so that there is no dead space in the root canal. The root canal is pretreated prior to plugging. The pretreatment of the root canal is performed by removing infection sources and other decayed materials from the root canal with a drilling device and a cleaning liquid, and forming the root canal to facilitate root canal plugging. The sizes of the Gutta-Percha cones were devised to be same as those of the root canal plugging devices so that plugging might be completed within short time. However, root canals have a very complex shape. The root canal may be curved. There are many root canals that have several branch root canal in addition to a main root canal. It is very hard to completely plug such root canals with Gutta-Percha cones. Since solid Gutta-Percha cones do not have fluidity, although they are useful in plugging the main root canal, it is not possible to use them in plugging the branch root canals.
“Plugging method with heat-softened Gutta-Percha” first introduced by Shilder on 1967 was welcomed by many experts. Various revisions of the plugging method with heat-softened Gutta Percha have been introduced. Even though they have some distadvantages, they are used widely in the clinic.
U.S. Pat. No. 4,265,618 by J. Marlin discloses a root canal plugging method in which a Gutta-Percha cone is inserted into a gun type injection device; the cone is softened; the softened Gutta-Percha is flowed into a root canal through a needle that is installed at the front part of the gun type device; the softened Gutta-Percha is vertically pressed by a plugger, etc. until it is hardened. The method has a disadvantage that not like the case of a solid Gutta-Percha cone, it is difficult to adjust the operating length. Specifically, softened Gutta Percha flows out of the Apicalforamen, resulting in pain of a patient.
U.S. Pat. No. 5,934,903 by J. Marlin discloses a needle for a gun type injection device. The front part of the gun type injection device, through which a plugging material is ejected, has a flange, and a needle, which has two different diameters along its length, is attached to the gun type injection device with a needle hub. While softened Gutta Percha flows smoothly since the needle was made of silver which has good heat conductivity, the needle tends to fracture in a procedure of bending and unbending the needle.
U.S. Pat. No. 4,527,560 by J. Masreliez discloses that a solid Gutta-Percha cone is adjusted to required operation length; a tip that is electrically heated is installed on a probe for dental or medical use; heating is performed at the end of the tip, and the tip is inserted into a root canal; and a Gutta-Percha cone is softened and plugs the root canal. The tip was made of stainless steel and was not elastic. Thus, it was not effective for plugging a curved root canal. Also Masreliez's invention has a disadvantage that it takes a long time to plug a root canal in the clinic.
U.S. Pat. No. 5,893,713 by Gary Garman et al. discloses a tip that is made of super-elastic material. However, it still had the problem of long plugging operation time.
Heating stability is essential for a plugging device in which a tip is connected to a probe and heated electrically. According to in-vitro tests with electrically heated tips, when an apparatus remain heated within a tooth for an extended time, damage may be caused in a certain tissue. It is desirable to minimize heating the root canal apex to avoid such damage. Thus, there has been a need to develop a root canal plugging device having improved controllability.